OBJECTIVETo investigate the lymph node metastasis pattern in pN1 stage gastric cancer patients and to analyze its risk factors.

METHODSClinicopathological data of 219 patients who underwent radical gastrectomy and were confirmed as pN1 stage gastric cancer between January 2013 and March 2016 were reviewed. All the patients underwent D2 or extended D2(D2+) lymphadenectomy. The overall metastatic rate was calculated. The risk factors associated with lymph node metastasis were analyzed. The pattern of skip lymph node metastasis and clinicopathological factors related to skip metastasis were analyzed.

RESULTSAmong 219 patients, 119 patients had only one metastatic lymph node, and 100 patients had two metastatic lymph nodes. The relatively higher sites of lymph node metastasis were station No.3[29.2%(64/219)], No.6[18.3%(40/219)] and No.4[11.4%(25/219)]. Compared to patients with tumor diameter ≤5 cm, metastatic rates of station No.3[39.4% (39/99) vs. 20.8%(25/120), P=0.003], No.4[16.2%(16/99) vs. 7.5%(9/120), P=0.045] and No.8[16.2%(16/99) vs. 6.7%(8/120), P=0.025] were significantly higher in those with tumor diameter >5 cm. Skip lymph node metastasis was detected in 56 cases(25.6%) and skip lymph node metastatic rate was significantly higher in patients with tumor diameter >5 cm [34.3%(34/99) vs. 18.3%(22/120), P=0.007]. Logistic regression analysis showed that the tumor size was an independent risk factor for the skip lymph node metastasis in pN1 stage gastric cancer (OR=1.982, 95%CI: 0.978 to 3.921, P=0.033).

CONCLUSIONSThe perigastric station No1 lymph node is the main site of early lymph node metastasis of pN1 stage gastric cancer. General pattern of lymph node metastasis is from proximus to distance, while quite a lot of skip lymph node metastases are observed. Tumor size is an important factor affecting the lymph node metastasis and bigger tumor may result in skip lymph node metastasis easily.